Lammoglia M A, Willard S T, Oldham J R, Randel R D
Texas Agricultural Experiment Station, Overton 75684, USA.
J Anim Sci. 1996 Sep;74(9):2253-62. doi: 10.2527/1996.7492253x.
Spring-calving Brahman cows (S) artificially inseminated to Brahman, Angus, or Tuli sires and fall-calving Brahman cows (F) naturally bred to Brahman were allotted randomly to receive 3.74% (LF; n = 9 S and 6 F), 5.20% (MF; n = 8 S and 6 F), or 6.55% dietary fat (HF; n = 8 S). Diets were formulated to contain differing fatty acid concentrations and to be isocaloric and isonitrogenous. Cows were bled and fed twice daily from 2 wk before expected calving date through d 21 after calving. Ultrasonography was performed on d 14 and 21 after calving. From d 21 to 90 after calving a sterile bull equipped with a chin-ball marker was placed with the cows to aid in estrus detection. In both seasons progesterone decreased (P < .01) and estradiol-17 beta increased (P < .01) as parturition approached. Cows receiving MF and HF had increased (P < .01) total numbers of follicles compared to LF cows, and cows receiving MF had larger (P < .01) follicles. During the spring, cows receiving HF and cows bred to Brahman or Tuli sires had longer (P < .01) gestation lengths. Progesterone concentrations before calving were affected (P < .01) by treatment x sire and estradiol-17 beta by a time x treatment interaction (P < .01). Cholesterol after calving was higher (P < .01) in HF cows than in LF or MF cows. In the fall, LF cows had heavier (P < .01) calves than cows receiving MF. Birth weight was also affected (P < .01) by treatment x sex of calf. Progesterone was affected (P < .01) by treatment x sex of calf. Estradiol-17 beta was affected (P < .01) by sex of calf and treatment x sex of calf. Across seasons, by d 90 after calving, 9 of 15 (60%) LF and 11 of 15 (73.3%) MF cows showed estrual behavior. Cows in the spring had increased (P < .01) numbers and larger follicles compared to the fall. In conclusion, dietary fat may influence steroid hormone concentrations before calving, calf birth weight and postpartum follicular populations; furthermore, follicular populations may also be influenced by season.
春季产犊的婆罗门牛（S）人工授精于婆罗门、安格斯或图利种公牛，秋季产犊的婆罗门牛（F）自然交配于婆罗门种公牛，将它们随机分配以接受3.74%（低脂肪组，LF；9头春季产犊牛和6头秋季产犊牛）、5.20%（中脂肪组，MF；8头春季产犊牛和6头秋季产犊牛）或6.55%的日粮脂肪（高脂肪组，HF；8头春季产犊牛）。日粮配方设计为含有不同的脂肪酸浓度，且能量和蛋白质含量相等。从预计产犊日期前2周直到产犊后21天，每天给母牛采血和喂食两次。在产犊后第14天和21天进行超声检查。从产犊后第21天到90天，将一头配备有下巴球标记器的无菌公牛与母牛放在一起，以帮助检测发情。在两个季节中，随着分娩临近，孕酮水平下降（P < 0.01），雌二醇-17β水平升高（P < 0.01）。与低脂肪组母牛相比，中脂肪组和高脂肪组母牛的卵泡总数增加（P < 0.01），且中脂肪组母牛的卵泡更大（P < 0.01）。在春季，高脂肪组母牛以及与婆罗门或图利种公牛配种的母牛妊娠期更长（P < 0.01）。产犊前孕酮浓度受处理×种公牛的影响（P < 0.01），雌二醇-17β受时间×处理交互作用的影响（P < 0.01）。产犊后，高脂肪组母牛的胆固醇水平高于低脂肪组或中脂肪组母牛（P < 0.01）。在秋季，低脂肪组母牛所产犊牛比中脂肪组母牛所产犊牛重（P < 0.01）。犊牛出生体重也受处理×犊牛性别的影响（P < 0.01）。孕酮受处理×犊牛性别的影响（P < 0.01）。雌二醇-17β受犊牛性别以及处理×犊牛性别的影响（P < 0.01）。在两个季节中，到产犊后90天时，15头低脂肪组母牛中有9头（60%）、15头中脂肪组母牛中有11头（73.3%）表现出发情行为。与秋季相比，春季母牛的卵泡数量增加且卵泡更大（P < 0.01）。总之，日粮脂肪可能会影响产犊前的类固醇激素浓度、犊牛出生体重和产后卵泡数量；此外，卵泡数量也可能受季节影响。
